Safety is an ever growing concern of the consumers and producers of motor vehicles. Many vehicles are now being manufactured with airbags as standard or optional equipment and it is expected that airbags will be standard equipment on all passenger motor vehicles in the near future. Typical vehicular airbags remain in a compacted, deflated state until activated. When the vehicle is subjected to a sudden and large deceleration caused by collision with another vehicle or a stationary object, the bag is quickly activated and inflates by rapid expansion of gases to create a deformable cushion between the driver and the interior of the vehicle, thereby mitigating injury to the driver.
The designer of an airbag safety system is faced with two competing requirements. First, the bag must inflate promptly and, almost instantly, after impact. On the other hand, the airbag must not inflate inappropriately, as may happen if the vehicle is nudged or bumped in traffic or travels over uneven terrain. An inappropriate inflation of the airbag may actually cause the driver to lose control of the vehicle and can lead to a severe accident. In view of these competing requirements, it is critical that the airbag system include an accurate sensor which will reliably generate an activation signal when the deceleration force to which the vehicle is subjected equals or exceeds a preset level, but will not generate the activation signal if the deceleration force falls below that level.
To this end, typical airbag systems employ one or more sensors. The most commonly used sensor comprises a ball and tube accelerometer in which a ball of a certain mass is normally held in a tube by a magnet disposed at one end thereof. When the device is subject to a decelerating force of sufficient magnitude, the ball will become dislodged from the magnet so as to roll to the other end of the tube and cause bridging of a pair of electrical terminals disposed thereat. The closing of the terminals produces a detectable electrical signal which may be used to trigger airbag inflation. Typically, a pair of these sensors are mounted on either side of the front bumper of the vehicle and the third sensor is mounted in the center of the vehicle at a location somewhat further toward the rear thereof. The third sensor acts as an override to prevent accidental activation of the airbag if the bumper sensors are subjected to relatively minor and localized deceleration. The three sensors are in electrical communication with a central processing unit which evaluates the signals therefrom and is programmed to generate an activation signal which triggers the airbag in appropriate circumstances.
The prior art sensors described herein above generally perform successfully in generating an airbag trigger signal under appropriate deceleration conditions; however, systems which employ these sensors can suffer from certain disadvantages when incorporated into a motor vehicle. For example, it is necessary to interconnect the sensors and airbag control unit of the vehicle by electrical wiring. If the sensors are provided in a prewired and preconnected form, handling and installation is very difficult and damage can easily occur. If the sensors are provided as separate units which are installed and later electrically interconnected, problems can also occur because of compromise of the connections. The sensors are typically mounted outside of the passenger compartment of the vehicle and hence are exposed to harsh environmental conditions which can include, dust, dirt, salt, water, oil and grease. Additionally, the sensors are subject to vibration and to impact by stray objects.
Various attempts have been made to seal airbag sensor connections. Ideally, the airbag sensor should be provided as a sealed unit which includes an internal connector and hence is devoid of trailing connectors or wires. This internal connector should establish electrical communication between the sensor and the remainder of the air system via a corresponding external connector in a manner which forms a tight environmental seal. U.S. Pat. No. 5,187,328 describes an environmentally sealed airbag sensor. Connection to this prior art airbag sensor is established via a male connector which has a sealing gasket associated therewith. It has been found that a better environmental seal can be achieved if the sealing gasket is associated with the female or internal portion of the connector; additionally, it has been found that the best environmental seal can be achieved if the sealing gasket employed with the connectors establishes its seal along a substantial portion of the length of the connectors as opposed to forming a mere butt seal.
Attempts to provide a female connector having an internal sealing gasket, particularly a gasket adapted to provide a sliding seal along the length of a mating connector have not been heretofore successful. It has generally been found that retention of the sealing gasket within the connector is very difficult. Proper sealing requires that there be a tight fit between the seal and the mating connector, when the connector is inserted. A tight fitting gasket tends to roll up or pop out. Additionally, it is quite difficult to install a sealing gasket within the female member of the connector pair.
Another problem associated with prior art connectors for airbag sensors arises from the fact that a number of different configurations and orientations of the sensor are employed. For example, accelerometers are often procured from various sources and the external configurations of these different sensors may vary. Additionally, the sensors are usually disposed in different orientations at different parts of the vehicle. Hence, connectors must be specific to different designs of sensor and even to different orientations of members of a group of similar sensors.
Accordingly, it will be appreciated that there is a need for an airbag sensor which includes a sealing gasket captively retained in the interior thereof to provide for a reliable environmental seal. It is also desirable that the connector be easy to assemble and that it be readily adaptable for a variety of sensor configurations and orientations.
The use of captive internal gaskets has previously been shown in the prior art; however, in no instance is there shown an environmentally sealable connector of the type disclosed herein. U.S. Pat. No. 4,717,355 discloses a moisture seal for a coaxial cable. The seal includes a sealing ring which engages a groove in the connector housing. The connector does not provide for sliding contact therepast and the gasket is not retained in a manner which would prevent it from pulling out or rolling up should sliding contact be established. U.S. Pat. No. 4,441,777 discloses a connector having a pair of swaging cones for sealing a wire in a coupling. The cones are not configured to allow for sliding insertion and withdrawal of the wire and are not fully retained in the connector. U.S. Pat. No. 4,857,007 discloses a connector having a sealing gasket retained in a groove. The gasket forms a butt seal and is not configured to provide a sliding seal and is retained in a manner which would not eliminate the problems with gasket pull out or roll up in the event that sliding contact therepast was established. U.S. Pat. Nos. 2,703,870; 3,603,912 and 3,517,373 disclose various electrical connectors having sealing members with trapezoidal cross sections. The sealing members are not retained in undercuts and cannot avoid the problem of gasket pull out or roll up.
The present invention provides for a connector assembly which includes a multi-part female connector having a housing with a gasket captively retained therein. The connector further includes a portion which seals the housing and retains the sensor assembly and terminals thereof. This portion may be readily configured to accommodate various designs and orientations of sensor. The connector of the present invention provides for a very secure environmental seal, is easy to use and assemble and can be readily adapted to a variety of applications. These and other advantages of the present invention will be readily apparent from the drawings, discussion and description which follow.